An example: RN R 50 H 1001 F M
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| RN |
R |
50 |
H |
1001 |
F |
M |
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| metal film resistor |
terminal type |
wattage rating |
characteristic |
resistance |
tolerance |
failure rate |
| 1 |
2 |
3 |
4 |
5 |
6 |
7 |
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1. RN =
metal film resistor
2. Terminal
type (high reliability)
- R = solderable leads
- C = solderable and weldable leads
- N = weldable leads
3. Wattage
rating
- 50 = 1/20 watt
- 55 = 1/10 watt
- 60 = 1/8 watt
- 65 = 1/4 watt
- 70 = 1/2 watt
- 75 = 1 watt
4. Characteristic:
(temperature coefficient) i.e., How much R will change per degree
centigrade or "parts per million" 9PPM)
- H = 50 PPM \
- J = 25 PPM > non
hermetically sealed resistors
- K = 100 PPM /
- C = 50 PPM \
-
> hermetically sealed resistors
- E = 25 PPM /
5. Resistance
value: First three digits are significant. The last
digit indicates the number of zeros: i.e.,
- 1001 = 100 with 1 zero = 1,000 Ohm
- 1002 = 100 with 2 zeros = 10,000 Ohm
- R = decimal point - 49R9 = 49.9 Ohm
6. Tolerance:
- F = 1 %
- D = 1/2 %
- B = 1/10 %
7. Failure
rate:
- M = 1.0 % @ 1000 hrs.
- P = 0.1 % @ 1000 hrs.
- R = 0.01 % @ 1000 hrs.
- S = 0.001 % @ 1000 hrs.
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